Rheostat



June 8 1926. 1,587,996

H. B. WARREN RHEOSTA'I' Filed Dec 31 1924 INVENTOR Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

HARRY B. WARREN, F COLLIERS, WEST VIRGINIA, ASSIGNOR TO WEIMEB-WARREN COMPANY, OF COLLIERS, WEST VIRGINIA, A CORPORATION OF WEST VIRGINIA.

RHEOSTAT.

Application filed December 31, 1924. Serial No. 759,058.

The invention relates to rheostats.

The principal object of this invention is to provide a rheostat which may be readily adjusted to current-consuming circuits which require current of different values. For example, the rheostat may be set to carry approximately 16 amperes at 250 volts, or approximately 8 amperes at 500 volts. The resistances may be used for starting direct-current motors, or for field rheostats, in electric welding circuits, and for many other uses readily apparent to those acquainted with the art to which this invention belongs.

It is one purpose of this invention to provide a number of resistance units of any suitable desi portion of t e units may be connected in series or parallel or both.

Referring to the accompanying drawing, Fig. 1 is a diagrammatic view of the invention, and Fig. 2 is a similar view with some or the parts in diiferent positions from those shown on Fig. 1.

On the drawing, 1 designates a bus-bar to which one terminal of each of a plurality of resistance units 2, 3, 4 and 5 are removably attached by bolts 6 provided with nuts 7. The remaining terminals of the resistance units are attached respectively to the switch blocks 8, 9, 10, and 11. The blocks 8 and 9 may be connected by the switch 12; the blocks 9 and 10, by the switch 13; and the blocks and 11, by the switch 14.

I provide the movable switch member 15 permanently in series with the motor having the series field 16 and the armature 17. The switch member 15 may engage the fixed contact 18 connected by the wire 19 to the busbar 1, or it may engage the fixed contact 20 which is connected by the wire 21 to the block 10.

The motor is shown connected by the wire 22 to the negative side of a source of current, and the block 9 is shown connected by the wire 23 to the positive side of the source of current.

In Fig. 1, all the switches are open. If the switches 12, 13, and 14 are closed and the switch-member 15 is closed on the contact 18, current from the positive Wire 23 flows in parallel through all the resistance units 2, 3, 4, and 5, and thence through the wire 19, the contact 18, the switch-member with means whereby all or a 15, the field winding 16, and the armature 17 to the negative wire 22. In this case it may be supposed that the motor receives a current of approximately 250 volts at 16 amperes.

Assuming, as shown in Fig. 2, that the switches 12 and 14 are closed, the switch 13 is open, and the switch-member 15 is closed on the contact 20. The current now flows in parallel through the resistance units 2 and 3 to the bus-bar 1 and thence in parallel through the resistance units 4 and 5. The current fiows in a series parallel relation through the resistance units, the current which flows through the units 2 and 3 in parallel flows to the units 4 and-5 through which it flows in parallel, the pair of units 2 and 3 now being in series with the pair of units 4 and 5. In Fig. 2 the current would be approximately 500 volts at 8 amperes, the horse-power remaining as before.

Assuming the switch-member 15 to be engaged with the contact 18, current will flow to the motor through the three resistance units 2, 3, and 4 in parallel, it the switch 14 is open and switches .12 and 13 are closed; and through the units 3, 4, and 5 in parallel if the switches 13 and 14 are closed, and the switch 12 is open; and through the units 2 and 3 in parallel if the switch 12 is closed and the switches 13 and 14 are open; and through the units 3 and 4 if the switch 13 is closed and the switches 12 and 14 are open; and through the unit 3 if the switches 12, 13 and 14 are open.

It is thus seen that by the employment of four resistance units, the resistance can be set for a large number of current values. The invention is not restricted to any definite number of resistance units. Some of the switches may be replaced by fixed conductors. For example, the. result obtained by Fig. 2, could be had by replacing the switches 12 and 14 by fixed conductors integral with the blocks.

The resistance can be adjusted by removing some of the resistance units or by adding some of them, which may be readily done by loosening or removing the proper nuts 7. The removal of a unit would be effecting the same change in the current flow as would be done by opening the proper switch to cutout the unit.

I claim nected to the bus-bar and the other to one of In a IheOSta a r, a plural ty of lethe said remaining ends of said units, and a sistance units, each having one end connectsecond'current supply line connected-to a n- W ed thereto, switches connecting the reinaiir other of the said remaining ends.

ing ends of the said units in series, a switch, In testimony whereof I hereunto aifix my a current supply Wire connected thereto, tWo signature this 29th dey of Dec, 1924a. contacts for the switch last named, one con- HARRY WARREN. 

